Inverter Integrated Electric Compressor

ABSTRACT

Provided is a low-cost compressor having excellent operation stability which enables the improvement of the stability of a control circuit by shielding electromagnetic noise and the effective prevention of the vibration of a control substrate while the design flexibility is maintained at the same high level as that of conventional ones. An inverter-integrated electric compressor in which a motor is incorporated and a high-voltage circuit for motor drive including an inverter and a control substrate provided with a low-voltage circuit for control are provided in a compressor housing is characterized in that a shield plate made of a material capable of shielding an electromagnetic noise emitted from the high-voltage circuit for motor drive toward the low-voltage circuit for control is interposed between the high-voltage circuit for motor drive and the control substrate, and the shield plate and the control substrate are fixed to each other and both are fixed at a predetermined position in the compressor housing.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an inverter-integrated electric compressor, and specifically relates to an inverter-integrated electric compressor in which its design flexibility is maintained at the same high level as that of conventional ones. The stability of its control circuit can be improved by shielding electromagnetic noise and its control substrate can be effectively prevented from vibrating, so as to achieve an excellent operational stability and low cost.

BACKGROUND ART OF THE INVENTION

As for an electric compressor, particularly for an electric compressor mounted on a vehicle, various vibration countermeasures to protect electrical components from malfunctions caused by long-time vibration have been suggested. For example, Patent document 1 discloses a structure of an electric compressor which incorporates a motor drive circuit including an inverter, in which the motor drive circuit is coated with a resin mold material, so as to be buried into the resin mold material.

In addition, an inverter-integrated electric compressor requires a means for shielding electromagnetic noises in case that electromagnetic noises emitted from a high-voltage circuit cause troubles such as malfunction of a control circuit consisting of low-voltage circuits. For example, Patent document 2 discloses a structure of a switching room of an inverter device, in which electromagnetic noises emitted from a high-voltage circuit toward a low-voltage circuit can be shielded by providing a magnetic shield between a power module as a high-voltage circuit and a power module drive circuit.

PRIOR ART DOCUMENTS Patent Documents

-   Patent document 1: JP2002-70743-A -   Patent document 2: JP-3729175-B

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In Patent document 2, though the stability of the electric circuit has been achieved by shielding the electromagnetic noise, any countermeasures against vibrations are neither referred to nor suggested.

Therefore an object of the present invention is to provide a low-cost compressor having excellent operation stability which can improve the stability of a control circuit by shielding electromagnetic noise and can effectively prevent the vibration of a control substrate while the design flexibility is maintained at the same high level as that of conventional ones.

Means for Solving the Problems

To achieve the above described object, an inverter-integrated electric compressor is an inverter-integrated electric compressor in which a motor is incorporated and a high-voltage circuit for motor drive including an inverter and a control substrate provided with a low-voltage circuit for control are provided in a compressor housing, characterized in that a shield plate made of a material capable of shielding an electromagnetic noise emitted from the high-voltage circuit for motor drive toward the low-voltage circuit for control is interposed between the high-voltage circuit for motor drive and the control substrate, and the shield plate and the control substrate are fixed to each other and both are fixed at a predetermined position in the compressor housing.

In such an inverter-integrated electric compressor, because the electromagnetic noise emitted from the high-voltage circuit for motor drive toward the low-voltage circuit for control is shielded by the shield plate, the low-voltage circuit for control can be surely prevented from malfunctioning caused by the electromagnetic noise and the compressor as a whole can be further stably operated. In addition, because the control substrate is fixed at the predetermined position in the compressor housing as mutually fixed to each other with the shield plate, the positional relation between the control substrate and the shield plate is maintained to a positional relation suitable for shielding the electromagnetic noise and the control substrate is prevented from vibrating. Therefore even in a high speed operation, the compressor operational stability can be surely maintained so that the compressor can be long-lived.

Because the shield plate according to the present invention can be shaped like a thin plate and does not require a large mounting space, it can be easily mounted on a conventional compressor and can be easily formed into a desirable shape according to a shape of its mounting section. Therefore, the design flexibility of a compressor can be maintained at a high level as almost the same level in a conventional case where the shield plate is not provided. Further, because the present invention can be realized substantively only by adding the shield plate, the operational stability of the compressor can be improved with a low cost, almost without changing the weight of the whole compressor. Furthermore, though the kind of the shield plate material according to the present invention is not limited, it is preferable to be made of a metal or an alloy because they can surely shield the electromagnetic noise and have excellent workability.

It is preferable that the shield plate is provided with a rib, though that is not always necessary. The rib improves the rigidity of the shield plate and prevents the control substrate from vibrating more effectively.

Further, it is preferable that at least a part of a fixing section of the shield plate to the control substrate is formed in a convex shape which is protruded toward the control substrate, though that is not always necessary. The convex-shaped fixing section can reduce the contact area between the control substrate and the shield plate in fixing them to each other, and the transmission of the vibration from the shield plate to the control substrate can be suppressed so as to suppress the vibration of the control substrate. As described later, in a case where an electric component including the high-voltage circuit for motor drive and the control substrate is provided in a housing space surrounded by the compressor housing, and a resin is filled in the housing space after assembling, the resin is filled into a gap formed between the control substrate and the shield plate by a protrusion of the fixing section, so that the control substrate can be firmly fixed to effectively prevent the vibration of the control substrate.

In the present invention, in a case where the high-voltage circuit for motor drive is provided with a noise filter at a power supply side, it is preferable that the shield plate is constructed so as to be able to shield also an electromagnetic noise emitted from the noise filter toward the low-voltage circuit for control, though that is not always necessary. Such a structure makes it possible that the malfunction of the low-voltage circuit for control caused by the electromagnetic noise is prevented more surely, so as to improve the operational stability of the whole compressor.

Further, in the present invention, in a case where the high-voltage circuit for motor drive is connected with a power source wire, it is preferable that the shield plate is constructed so as to be able to shield also an electromagnetic noise emitted from the power source wire toward the low-voltage circuit for control, though that is not always necessary. Such a structure makes it possible that the malfunction of the low-voltage circuit for control caused by the electromagnetic noise is prevented yet more surely, so as to improve the operational stability of the whole compressor.

In order to achieve the circuit insulation and the vibration prevention of the electric component, the inverter-integrated electric compressor according to the present invention can be configured such that an electric component including the high-voltage circuit for motor drive and the control substrate is provided in a housing space surrounded by the compressor housing, and a resin is filled in the housing space after assembling and where at least a part of the electric component is sealed with a filled resin having been solidified. In such a configuration it is preferable that a hole for venting air is provided in the shield plate to fill the resin uniformly into the housing space, though that is not always necessary. Such a hole for venting air can prevent the air from either generating or remaining, and therefore the electric component, which is sealed with the resin in the housing space, can be fixed more firmly so as to improve the operational stability of the whole compressor.

As described above, in a case where the housing space for filling the resin is provided in the compressor, it is preferable that the shield plate is provided with a hole for filling the resin, though that is not always necessary. Such a hole for filling the resin makes it possible that the resin can be poured even into a part covered by the shield plate, so that the resin is surely filled wholly into a predetermined section in the housing space. Therefore the electric component, which is sealed with the resin in the housing space, can be fixed more firmly so as to improve the operational stability of the whole compressor. Besides, the hole for filling the resin may have even another purpose for venting air, and alternatively, they may be different holes.

Because the inverter-integrated electric compressor according to the present invention can achieve excellent operational stability by shielding the electromagnetic noise and vibration prevention of the control substrate, it is suitable as a compressor for vehicles, and specifically suitable for a compressor used in an air conditioning system for vehicles, which tends to be affected by vibrations, though its application is not limited.

Effect According to the Invention

Thus the present invention makes it possible, as its design flexibility is maintained at the same high level as that of conventional ones, that the stability of its control circuit can be improved by shielding electromagnetic noise and its control substrate can be effectively prevented from vibrating, so as to achieve excellent operational stability and low cost.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a schematic longitudinal sectional view of an inverter-integrated electric compressor according to an embodiment of the present invention.

FIG. 2 is a perspective view of a housing space forming part, a shield plate and a control substrate in the inverter-integrated electric compressor shown in FIG. 1.

FIG. 3 is a circuit diagram for exemplifying a part to provide a shield plate in the inverter-integrated electric compressor shown in FIG. 1.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, desirable embodiments of the present invention will be explained as referring to figures.

FIG. 1 shows an inverter-integrated electric compressor according to an embodiment of the present invention, specifically as an application of the present invention to a scroll-type electric compressor. In FIG. 1, inverter-integrated electric compressor 1 is provided with compression mechanism 2 consisting of fixed scroll 3 and movable scroll 4. Movable scroll 4 can be swung relative to fixed scroll 3 in a condition where its rotation is prevented with ball coupling 5. Motor 7 is incorporated in compressor housing (center housing) 6, and built-in motor 7 drives main shaft 8 (rotation shaft) to rotate. The rotational movement of main shaft 8 is converted into the orbital swinging movement of movable scroll 4, through eccentric pin 9 and eccentric bush 10 which is rotatably engaged therewith. In this embodiment, compressor housing (front housing) 12 is provided with suction port 11 for sucking refrigerant as fluid to be compressed. Sucked refrigerant is led to compression mechanism 2 through a placement part of motor 7. The refrigerant which has been compressed with compression mechanism 2 is delivered to an external circuit, through discharge hole 13, discharge chamber 14 and discharge port 16 which is provided in compressor housing (rear housing) 15.

Housing space 20 is formed by surrounding an extended section of compressor housing 12 (front housing), and motor drive circuit is provided in housing space 20. In more detail, motor drive circuit 21 is provided at the external side of partition wall 22 which is formed in compressor housing 12 against the side of refrigerant suction passageway. Motor drive circuit 21 supplies electricity through seal terminal 23 (an output terminal of motor drive circuit 21), which is attached thereto by penetrating partition wall 22, and lead wire 24 to motor 7, while the refrigerant suction passageway side and the side of motor drive circuit 21 are sealed in the placement part of seal terminal 23. In this embodiment, because motor drive circuit 21 is provided at the external side of partition wall 22, at least one part of electric components including motor drive circuit 21 can be cooled with sucked refrigerant through partition wall 22 by heat exchange. Such a configuration can make a structure simple because electric components, such as high-voltage circuit 25 for motor drive having inverter function, which tend to generate heat can be automatically cooled adequately to maintain a predetermined specification of motor drive circuit 21 without providing another cooling device. In addition, such a configuration is applicable to all types of inverter-integrated electric compressor which compresses refrigerant as a fluid to be compressed, as well as scroll-type electric compressor.

Motor drive circuit 21 includes high-voltage circuit 25 for motor drive which has an inverter function and control substrate 26 which has a low-voltage circuit for control, and electric components such as capacitor 27 are provided either integrally with it or separately from it. Because shield plate 31, which can shield electromagnetic noises, is interposed between high-voltage control circuit 25 for motor drive and control substrate 26, the low-voltage circuit for control provided on the control substrate can be surely protected from the electromagnetic noise emitted from high-voltage circuit 25 for motor drive, so that troubles such as malfunction are prevented. In addition, control substrate 26 is fixed to convex fixing section 32 provided on shield plate 31, so as to be prevented from vibrating. Therefore shield plate 31 can improve the electrical stability of the circuit and the physical stability of the electrical component, so as to achieve an electric compressor excellent in operational stability. Further, shield plate 31 is provided with vent hole 33, which can be used even for filling resin as described later.

Motor drive circuit 21 is connected to an external power supply (not shown) with connector 28 as an input terminal. The aperture side to the outside of compressor housing 12, which mounts these electric components including motor drive circuit 21, is covered as sealed with lid member 29, and these electric components are protected by lid member 29.

Motor drive circuit 21 and electric components, such as capacitor 27, are placed in housing space 20 and then, resin 34 is filled. Solidified resin 34 seals substantively a whole of them. As shown in the figure, the resin filling is limitedly performed in a minimum range of housing space 20 in view of lightweight of compressor 1 as a whole. Shield plate 31 is provided with vent hole 33 which can be used even for filling resin as described above, therefore generating and remaining of bubbles in filled resin 34 are effectively prevented. Further, vent hole 33 can be even used for a hole through which resin is filled. Furthermore, a gap is formed by convex fixing section 32 between shield plate 31 and control substrate 26. Therefore the resin filling can be surely achieved even at a portion shielded by control substrate 26 or shield plate 31, so that electric components, which are sealed in housing space 20, are fixed surely and the operational stability of compressor 1 can be improved as a whole.

FIG. 2 shows a schematic relation among housing space 20, shield plate 31 and control substrate 26 in the inverter-integrated electric compressor shown in FIG. 1. Control substrate 26 having a low-voltage circuit for control is fastened to fixing section 32 formed on shield plate 31 with screw 36. As to shield plate 31, the rigidity has been improved by forming rib 35, and the vibrational transmission has been reduced by forming some fixing sections 32 into convex shapes so as to minimize the contact area of control substrate 26. As described above, vent hole 33, which can be even used for a hole for the resin filling, prevents bubbles from generating in filled resin 34, so that electric components which are sealed in housing space 20 are fixed more surely.

High-voltage circuit 25 for motor drive placed in housing space 20 is connected through noise filter 37 to power source wire 38, so as to be protected from conductive noises of the signal wire emitted from power source wire 38. Because these electric components are supplied with high-voltage electric power through power source wire 38 from an external power supply, electromagnetic noises, which are strong enough to affect other electric components, may be emitted to the surroundings. Hence shield plate 31 attached to control substrate 26 is configured as being able to shield electromagnetic noises emitted from noise filter 37 and power source wire 38, as well as high-voltage circuit 25 for motor drive. Therefore the low-voltage circuit for control, which is provided on control substrate 26, can be protected and compressor is ensured to be operated stably.

Such a configuration can be described like an electric circuit as shown in FIG. 3. In FIG. 3, electric compressor 1 is provided with motor drive circuit 21 as described above, and motor 7 is driven to rotate by supplying the output from motor drive circuit 21 through seal terminal 23 and lead wire 24 into each motor wire wrap 41 of built-in motor 7, so that the compression is performed with compression mechanism 2. Motor drive circuit 21 comprises high-voltage circuit 25 for motor drive and low-voltage circuit 45 for control, which has motor control circuit 44 to control each power element 43 (switching element) of inverter 42 in high-voltage circuit 25 for motor drive, and low-voltage circuit 45 for control is provided on control substrate 26. Electric power is supplied from external power supply 46, such as a battery, into high-voltage circuit 25 for motor drive through connector 47 for high-voltage, and then is supplied through smoothing capacitor 27 into inverter 42. The direct current input from external power supply 42 is converted into pseudo-triphase current, and then supplied to motor 7. Low-voltage electric power is supplied through connector 49 for control signal into motor control circuit 44, for example, from automotive air conditioning control device 48. In FIG. 3, connector 49 for control signal and connector 47 for high-voltage are illustrated at positions apart from each other, but actually, are mounted in the same connector 28 shown in FIG. 1. Shield plate 31, which is fixed to control substrate 26, is interposed between high-voltage circuit 25 for motor drive and control substrate 26 with low-voltage circuit 45 for control, and it covers over high-voltage circuit 25 for motor drive as much as possible so as to block the effect of noise on the side of low-voltage circuit 45 for control from high-voltage circuit 25 for motor drive.

INDUSTRIAL APPLICATIONS OF THE INVENTION

The present invention is applicable to all types of inverter-integrated electric compressor, and specifically suitable for an inverter-integrated electric compressor for automotive air conditioning systems which requires excellent operation stability, excellent vibration durability, high design flexibility and achievement of downsizing and lightweight.

EXPLANATION OF SYMBOLS

-   1: inverter-integrated electric compressor -   2: compression mechanism -   3: fixed scroll -   4: movable scroll -   5: ball coupling -   6: compressor housing (center housing) -   7: motor -   8: main shaft -   9: eccentric pin -   10: eccentric bush -   11: suction port -   12: compressor housing (front housing) -   13: discharge hole -   14: discharge chamber -   15: compressor housing (rear housing) -   16: discharge port -   20: housing space -   21: motor drive circuit -   22: partition wall -   23: seal terminal -   24: lead wire -   25: high-voltage circuit for motor drive -   26: control substrate -   27: capacitor -   28: connector -   29: lid member -   31: shield plate -   32: fixing section -   33: vent hole -   34: filled resin -   35: rib -   36: screw -   37: noise filter -   38: power source wire -   41: motor wire wrap -   42: inverter -   43: power element (switching element) -   44: motor control circuit -   45: low-voltage circuit for control -   46: external power supply -   47: connector for high-voltage -   48: air conditioning control device -   49: connector for control signal 

1. An inverter-integrated electric compressor in which a motor is incorporated and a high-voltage circuit for motor drive including an inverter and a control substrate provided with a low-voltage circuit for control are provided in a compressor housing, wherein a shield plate made of a material capable of shielding an electromagnetic noise emitted from said high-voltage circuit for motor drive toward said low-voltage circuit for control is interposed between said high-voltage circuit for motor drive and said control substrate, and said shield plate and said control substrate are fixed to each other and both are fixed at a predetermined position in said compressor housing.
 2. The inverter-integrated electric compressor according to claim 1, wherein said shield plate is provided with a rib.
 3. The inverter-integrated electric compressor according to claim 1, wherein at least a part of a fixing section of said shield plate to said control substrate is formed in a convex shape which is protruded toward said control substrate.
 4. The inverter-integrated electric compressor according to claim 1, wherein said high-voltage circuit for motor drive is provided with a noise filter at a power supply side, and said shield plate is constructed so as to be able to shield also an electromagnetic noise emitted from said noise filter toward said low-voltage circuit for control.
 5. The inverter-integrated electric compressor according to claim 1, wherein said high-voltage circuit for motor drive is connected with a power source wire, and said shield plate is constructed so as to be able to shield also an electromagnetic noise emitted from said power source wire toward said low-voltage circuit for control.
 6. The inverter-integrated electric compressor according to claim 1, wherein an electric component including said high-voltage circuit for motor drive and said control substrate is provided in a housing space surrounded by said compressor housing, a structure is given where a resin is filled in said housing space after assembling and where at least a part of said electric component is sealed with a filled resin having been solidified, and a hole for venting air is provided in said shield plate to fill said resin uniformly into said housing space.
 7. The inverter-integrated electric compressor according to claim 6, wherein said shield plate is provided with a hole for filling said resin.
 8. The inverter-integrated electric compressor according to claim 1, wherein said compressor is one mounted on a vehicle.
 9. The inverter-integrated electric compressor according to claim 8, wherein said compressor is one for an air conditioning system for vehicles. 